This Nonprovisional application claims priority under 35 U.S.C. § 119(a) on Patent Application No. 2003-085630 filed on Mar. 26, 2003 and No. 2003-082913 filed on Mar. 25, 2003 in JAPAN, the entire contents of which are hereby incorporated by reference.
The present invention relates to various electronic equipments such as mobile phones, cordless phones or PDA (Personal Digital Assistant: mobile information terminal), a backlight structure that can be used suitably in these electronic equipments and can provide unique emission colors, and a keypad for an electronic equipment that is suitable for such a backlight structure.
In recent years, design has become increasingly important in order to provide satisfaction from owning an electronic equipment as above, and the “cover changeable” type in which a housing cover can be exchanged to meet the diversity of tastes of users has become popular. Not only for housing covers, but also for other portions of the equipment, it is advantageous to increase the degree of freedom of design in order to provide satisfaction to the users.
On the other hand, an electronic equipment as above tends to include a mechanism for illuminating a display panel or operation keys so that the equipment can be operated even in a dark environment.
Conventionally, one example of known techniques for illuminating a plurality of keytops with a few number of LEDs is that an optical waveguide for backlight is provided inside a housing, light from a few number of LEDs is supplied to a plurality of keytops via the optical waveguide and the visibility in a dark environment is improved (e.g., Japanese Laid-Open Patent Publication No. 2001-167655).
FIG. 8 is a cross-sectional view of an operation key and its periphery in an electronic equipment 10, which is one example of such a conventional art.
As shown in FIG. 8, a thin plate-like printed substrate 7 is disposed parallel to a housing 5 below the inner surface of the housing 5 of the electronic equipment 10, and an opening portion 5a for operation key arrangement is formed on the upper surface of the housing 5.
A chip-like LED 2 is disposed in a position apart from the portion immediately below the opening portion 5a on the printed substrate 7, so that visible light for illuminating the operation key can be emitted. Furthermore, a keytop 3a is disposed as an operation key having substantially the same size as that of the opening portion 5a immediately below the opening portion 5a on the printed substrate 7. The keytop 3a is formed such that its upper surface is flat and is slightly projected from the opening portion 5a to the outside of the housing 5.
Furthermore, a flexible optical waveguide 3 is disposed so as to fill the remaining space between the inner surface of the housing 5 and the printed substrate 7, and the light emitted from the LED 2 is guided through the optical waveguide 3 to surrounding portions. In FIG. 8, the keytop 3a and the optical waveguide 3 are formed into one piece, but the present invention is not limited thereto, and the keytop 3a can be a separate transparent or semi-transparent member having translucent properties.
The light emitted from the LED 2 is guided to the keytop 3a through the optical waveguide 3 and further guided out from the keytop 3a to the outside of the electronic equipment 10, so that this light can be seen from the outside of the electronic equipment 10. The operation key is illuminated with this structure.
A swallow bowl-like recess 3b is formed on the lower surface of the keytop 3a, and the bottom portion of the recess 3b is flat. A thin plate-like conductor 6 is disposed in the flat portion of the bottom portion, and when the keytop 3a is pressed down by the operation of a user, the flexible optical waveguide 3 is bent and the conductor 6 disposed in the recess 3b is brought in contact with a contact point (not shown) disposed on the upper surface of the printed substrate 7 so that the switch is turned on. Thus, the key operation of the user can be detected by control means (not shown) of the electronic equipment 10.
FIG. 9 is a schematic view of a mobile phone 20 in which an example of another conventional art is used. FIG. 10A is a cross-sectional view showing the outline of the internal structure of the mobile phone 20. FIG. 10B is a partially enlarged cross-sectional view (ten key portion) showing the outline of the internal structure of the mobile phone 20.
In this mobile phone 20, a ten key portion 20a and a liquid crystal screen portion 20b provided in a mobile phone main body 21 are configured so as to emit light when they are in use or in other occasions. For this, a backlight structure 30 is provided inside the mobile phone main body 21.
The backlight structure 30 for the ten key portion 20a and the liquid crystal screen portion 20b has the structure as shown in FIGS. 10A and 10B. More specifically, the ten key portion 20a is configured such that LEDs 2 are provided in a printed substrate 7 provided inside the mobile phone main body 21, and light from the LEDs 2 is transmitted through respective keypads 23 constituting the ten key portion 20a and is emitted. The liquid crystal screen portion 20b is configured such that a liquid crystal cell 8 is provided in the printed substrate 7 via a backlight waveguide plate 9, and light from a LED 2a provided adjacent to the backlight waveguide plate 9 is transmitted through the backlight waveguide plate 9 and is emitted.
In such a backlight structure 30, visible light chips are used for the LEDs 2 and the LED 2a. 